What causes cancer? It's all in the genes

While cancer may have many causes (exposure to radiation and hormone replacement therapy during menopause are known examples) and often takes years to develop, all forms of the disease ultimately result from serious damage (mutations) to cells’ DNA.

Sometimes, mutated DNA is inherited. In the case of familial breast cancer, either of two recently discovered rogue genes (BRCA1 and BRCA2) can be detected in a minority of cases. However, it is likely that many other, as yet undiscovered, genes are linked to a strong family history of breast cancer.

Although cells from many malignant tumors can be seen under the microscope to have cancer-linked alterations in the number or structure of the 24 pairs of chromosomes on which our genes reside, in other instances no changes are obvious. In either case, knowing which of the tens of thousands of “active” human genes on those chromosomes actually trigger the disease and/or cause it to progress and ultimately kill has largely eluded our understanding.

Now, a study just published in the prestigious journal Nature takes us an exciting step closer to that goal. Using the latest technology to map the entire DNA in a patient with acute leukemia, a team of scientists based at Washington University in St. Louis has identified ten mutated genes specific to the leukemia cells.

They accomplished this feat by comparing the thousands of genes in the patient’s malignant white cells (called myeloblasts or, simply, “blasts”) to those in her normal skin cells. They also compared the “blast” genes to the entire DNA belonging to two other humans: J. Craig Venter (who won the race to map the human genome and was then the first to have his own DNA mapped) and James D. Watson (co-discoverer, with Francis Crick and Rosalind Franklin, of the structure of DNA).